Background: Given that adults with ADHD continue to use stimulants for extended periods of time, studies on the long-term effectiveness and adverse events are warranted. The aims of this study were to investigate factors associated with persistence in treatment in an exploratory manner and to document side effects and reasons for discontinuation.

Method: The current study describes the systematic follow-up of 133 psychiatric patients with DSM-IV–diagnosed ADHD treated with central stimulants at a specialized outpatient unit between January 1, 2001, and August 31, 2006. A standardized questionnaire, derived from the Targeted Attention-deficit Disorder Symptoms Rating Scale, was used in order to measure improvement of the following target symptoms: hyperactivity, impulsivity, irritability, distractibility, structure/organization problems, inattention, and restlessness.

Results: Eighty percent of the patients were successfully treated with stimulants at the 6- to 9-month follow-up. Fifty percent remained in treatment after 2 years or more. Forty-five percent were treated for comorbid anxiety and/or depression during the study period. Only 15% dropped out because of lack of efficacy. The amount of clinical response over the first 6 to 9 months (but not at 6 weeks) predicted adherence to treatment at 2 years. The patients’ heart rate increased from a least squares mean±SE of 70±2.2 to 80±2.1 bpm (P=.00003) while blood pressure remained unchanged at the≥2-year follow-up. Severe side effects or drug abuse were not detected in this cohort.

Conclusions: The long-term treatment outcome shows that stimulants are effective in adult ADHD and side effects tend to be mild.